In various industries, such as in the computer industry, there is a need for low cost high performance heat exchangers to cool such components as microprocessors or semiconductors. Many semiconductors create so much heat that they can be irreparably damaged if the heat is not removed. Consequently, heat exchangers employing heat sinks have been used to pull the heat away from the semiconductor and disperse that heat into the atmosphere.
One type of heat sink used with semiconductors is a simple aluminum extrusion screwed down or clamped to the semiconductor. The extrusion typically has a flat bottom plate which contacts the semiconductor and a plurality of fins or parallel protrusions extending from the plate in a comb-type configuration. Such extrusions have many limitations, including the height of the fins being limited by the thicknesses of the fins. The number of fins per square inch is limited by the thickness and the height. Such limitations on the density of the fins on such extrusions reduces the efficiency of the heat removal.
A significantly improved heat sink has been designed particularly for use with fanned heat exchangers. This heat sink employs a "folded fin" configuration wherein the folded fin is clamped or bonded to a thermally conductive plate to form a heat sink assembly. In particular, a folded fin heat sink is formed by a sheet of aluminum or other heat conductive material which is folded into a wave-like pattern forming an alternating series of ridges and troughs (grooves). The folded fin may be placed directly on a substrate to be cooled or on a separate conductive base plate to form the heat sink assembly. This folded fin design offers high thermal conductivity, extremely large surface area and low costs. By taking advantage of the large surface area, less air flow is required to meet industry standard thermal specifications.
The present invention is directed to an improved folded fin-type heat exchanger which reduces air back pressure and improves the efficiency of the heat sink. The invention is particularly applicable for use with fanned heat exchangers, and the improved heat sink is capable of reducing the fan RPM and, thereby, reduce the fan noise.